A multifluid perspective on multimessenger modelling

TL;DR

This paper reviews the concept of relativistic multifluid systems in astrophysics, illustrating their applications in neutron star phenomena, gravitational waves, and electromagnetic coupling, aiming to clarify complex multifluid interactions.

Contribution

It introduces the multifluid framework for modeling various astrophysical phenomena, highlighting less familiar aspects and establishing a common language for future research.

Findings

Application to superfluid hydrodynamics in pulsars

Insights into neutron star cooling via heat flow models

Discussion on matter-electromagnetism coupling in explosive events

Abstract

This brief review introduces the notion of a relativistic multifluid system -- a multi-component system with identifiable relative flows -- and outlines a set of models for scenarios relevant for different astronomical observation channels. The specific problems used to illustrate the key principles include superfluid hydrodynamics (with relevance for radio and x-ray pulsar timing and gravitational-wave searches), heat flow (connecting to the problem of neutron star cooling and associated x-ray observations) and the coupling between matter and electromagnetism (linking to explosive phenomena like gamma-ray bursts and more subtle issues like the long-term evolution of a neutron star's magnetic field). We also comment on the coupling between matter and radiation, for which the multifluid approach would seem less appropriate. The main motivation of the survey is to illustrate less familiar aspects that come into play in multifluid problems, establish the relevant "language" and provide a platform for more detailed work on these issues.